T-shaped cutter, rib-machining method and airplane part

Abstract

On the perimeter of a head ( 14 ) that is bonded on one end of the shank ( 12 ) of a T-shaped cutter, multiple end cutting edge sections ( 16 ) with a cutting edge ( 16 a ) on the tip side of the T-shaped cutter ( 10 ) and multiple upper edge sections ( 18 ) with a cutting edge ( 18 a ) on the base end side are disposed alternating in the circumferential direction of the T-shaped cutter. The cutting edges ( 16 a, 18 a ) of the end cutting edge sections ( 16 ) and the upper edge sections ( 18 ) form an integral structure with the shank ( 12 ) and the head ( 14 ).

The invention claimed is: 
     
       1. A method of forming a rib having an overhanging part by cutting a workpiece made of an aluminum alloy, the method comprising:
 providing a T-cutter, which comprises a shank and a head provided at an end of the shank, the head defining a plurality of bottom edge parts and top edge parts alternately arranged in a peripheral direction of the T-cutter, each of the bottom edge parts having a cutting edge formed by a ridgeline defined by intersection between a rake face of the bottom edge part, and a bottom face, a side face, and an R-corner therebetween of the bottom edge part, each of the top edge parts having a cutting edge formed by a ridgeline defined by intersection between a rake face of the top edge part, and a top face, a side face, and an R corner therebetween of the top edge part, 
 forming a rib part of said workpiece, while the workpiece is mounted to a table of a five-axis machine tool having three linear feed axes and two rotational feed axes, by using an end mill attached to a spindle, while leaving a thickness of at least a width of said overhanging part; 
 attaching the T-cutter, with said shank and said head, to the spindle of the five-axis machine tool, rotating the spindle; and 
 moving said workpiece mounted to the table of the five-axis machine tool and said T-cutter relative to each other under five-axis control of the five-axis machine so as to form the overhanging part in a form of a three-dimensional undercut shape defined by a curved surface which is slanted with respect to a plane vertical to an axial line of the T-cutter, after determining processing conditions so as to remove 100 cm to 1000 cm of material from the workpiece per minute.